I too can confirm this bug after trying to add an AAC from nero with x264 video

from command line:
MP4Box -inter 500 -add file.aac -add file.264 file.mp4 -fps 29.9699

*** buffer overflow detected ***: MP4Box terminated
======= Backtrace: =========
/lib/libc.so.6(__fortify_fail+0x4b)[0xb7c91fdb]
/lib/libc.so.6[0xb7c90040]
/lib/libc.so.6[0xb7c8f285]
/usr/lib/libgpac-0.4.4.so(chpl_New+0x50)[0xb7e14da0]
/usr/lib/libgpac-0.4.4.so(gf_isom_box_new+0x715)[0xb7e33265]
/usr/lib/libgpac-0.4.4.so(gf_isom_parse_box+0x13d)[0xb7e3446d]
/usr/lib/libgpac-0.4.4.so(udta_Read+0x60)[0xb7e15ff0]
/usr/lib/libgpac-0.4.4.so(gf_isom_box_read+0xbd)[0xb7e3003d]
/usr/lib/libgpac-0.4.4.so(gf_isom_parse_box+0x279)[0xb7e345a9]
/usr/lib/libgpac-0.4.4.so(gf_isom_read_box_list+0x3d)[0xb7e34a5d]
/usr/lib/libgpac-0.4.4.so(moov_Read+0x2e)[0xb7e1734e]
/usr/lib/libgpac-0.4.4.so(gf_isom_box_read+0x977)[0xb7e308f7]
/usr/lib/libgpac-0.4.4.so(gf_isom_parse_box+0x279)[0xb7e345a9]
/usr/lib/libgpac-0.4.4.so(gf_isom_parse_root_box+0x52)[0xb7e34b42]
/usr/lib/libgpac-0.4.4.so(gf_isom_parse_movie_boxes+0x96)[0xb7e3b686]
/usr/lib/libgpac-0.4.4.so(gf_isom_open_file+0xe7)[0xb7e3ba27]
/usr/lib/libgpac-0.4.4.so(gf_isom_open+0x4f)[0xb7e3f90f]
/usr/lib/libgpac-0.4.4.so(gf_media_import+0xb0)[0xb7eb7b90]
MP4Box[0x8061f6f]
MP4Box[0x804ef28]
/lib/libc.so.6(__libc_start_main+0xe5)[0xb7bc5685]
MP4Box[0x804cea1]
======= Memory map: ========
08048000-0806f000 r-xp 00000000 08:01 1418       /usr/bin/MP4Box
0806f000-08071000 r--p 00026000 08:01 1418       /usr/bin/MP4Box
08071000-08072000 rw-p 00028000 08:01 1418       /usr/bin/MP4Box
08072000-08093000 rw-p 08072000 00:00 0          [heap]
b79c2000-b79cf000 r-xp 00000000 08:01 46666      /lib/libgcc_s.so.1
b79cf000-b79d0000 r--p 0000c000 08:01 46666      /lib/libgcc_s.so.1
b79d0000-b79d1000 rw-p 0000d000 08:01 46666      /lib/libgcc_s.so.1
b79da000-b79dc000 rw-p b79da000 00:00 0
b79dc000-b79de000 r-xp 00000000 08:01 45711409   /lib/libdl-2.8.90.so
b79de000-b79df000 r--p 00001000 08:01 45711409   /lib/libdl-2.8.90.so
b79df000-b79e0000 rw-p 00002000 08:01 45711409   /lib/libdl-2.8.90.so
b79e0000-b79f4000 r-xp 00000000 08:01 45711432   /lib/libpthread-2.8.90.so
b79f4000-b79f5000 r--p 00013000 08:01 45711432   /lib/libpthread-2.8.90.so
b79f5000-b79f6000 rw-p 00014000 08:01 45711432   /lib/libpthread-2.8.90.so
b79f6000-b79f8000 rw-p b79f6000 00:00 0
b79f8000-b7b2a000 r-xp 00000000 08:01 10679      /usr/lib/i686/cmov/libcrypto.so
.0.9.8
b7b2a000-b7b32000 r--p 00132000 08:01 10679      /usr/lib/i686/cmov/libcrypto.so
.0.9.8
b7b32000-b7b3f000 rw-p 0013a000 08:01 10679      /usr/lib/i686/cmov/libcrypto.so
.0.9.8
b7b3f000-b7b43000 rw-p b7b3f000 00:00 0
b7b43000-b7b85000 r-xp 00000000 08:01 10680      /usr/lib/i686/cmov/libssl.so.0.
9.8
b7b85000-b7b86000 r--p 00041000 08:01 10680      /usr/lib/i686/cmov/libssl.so.0.
9.8
b7b86000-b7b89000 rw-p 00042000 08:01 10680      /usr/lib/i686/cmov/libssl.so.0.
9.8
b7b89000-b7bad000 r-xp 00000000 08:01 45711411   /lib/libm-2.8.90.so
b7bad000-b7bae000 r--p 00023000 08:01 45711411   /lib/libm-2.8.90.so
b7bae000-b7baf000 rw-p 00024000 08:01 45711411   /lib/libm-2.8.90.so
b7baf000-b7cec000 r-xp 00000000 08:01 45711403   /lib/libc-2.8.90.so
b7cec000-b7cee000 r--p 0013d000 08:01 45711403   /lib/libc-2.8.90.so
b7cee000-b7cef000 rw-p 0013f000 08:01 45711403   /lib/libc-2.8.90.so
b7cef000-b7cf3000 rw-p b7cef000 00:00 0
b7cf3000-b7d07000 r-xp 00000000 08:01 5538       /usr/lib/libz.so.1.2.3.3
b7d07000-b7d09000 rw-p 00013000 08:01 5538       /usr/lib/libz.so.1.2.3.3
b7d09000-b7f83000 r-xp 00000000 08:01 2628       /usr/lib/libgpac-0.4.4.so
b7f83000-b7f84000 r--p 0027a000 08:01 2628       /usr/lib/libgpac-0.4.4.so
b7f84000-b7f88000 rw-p 0027b000 08:01 2628       /usr/lib/libgpac-0.4.4.so
b7f88000-b7f8a000 rw-p b7f88000 00:00 0
b7f91000-b7f95000 rw-p b7f91000 00:00 0
b7f95000-b7faf000 r-xp 00000000 08:01 45711372   /lib/ld-2.8.90.so
b7faf000-b7fb0000 r-xp b7faf000 00:00 0          [vdso]
b7fb0000-b7fb1000 r--p 0001a000 08:01 45711372   /lib/ld-2.8.90.so
b7fb1000-b7fb2000 rw-p 0001b000 08:01 45711372   /lib/ld-2.8.90.so
bf983000-bf9b1000 rw-p bffd2000 00:00 0          [stack]